Underactive thyroid - How do doctors diagnose an underactive thyroid?
BMJ Group Medical Reference
To check whether you have an underactive thyroid gland, your doctor will ask you some questions, examine your neck, and do some blood tests.
Questions your doctor might ask
Your doctor might ask you some of these questions.
Do you feel very tired?
Have you put on weight?
Do you have constipation?
Do you feel extra sensitive to cold?
If you are a woman, are your periods heavier than usual?
Have you noticed a swelling in your neck?
Your doctor might ask you when your symptoms started, and if they all started at the same time. He or she might also ask you about changes to your hair, skin, and voice.
Your doctor will probably ask whether any members of your family have thyroid problems. He or she will also want to know about any operations or x-rays you've had, any illnesses you've had, and any medicines you're taking.
Your doctor will examine your neck to see if your thyroid gland is bigger than usual. Your doctor may also:
Measure your weight
Examine your skin and hair
Test the strength of your muscles
Check your blood pressure and pulse. This is because an underactive thyroid gland can affect your heart.
Tests your doctor might order
Your doctor will order blood tests to check the levels of hormones in your blood. These hormones are thyroid-stimulating hormone (TSH) and thyroxine (T4). If you have more TSH than normal, or less T4, you may have an underactive thyroid gland.
If your TSH level is only slightly raised and your T4 level is normal, you may have mild hypothyroidism.
Your doctor will also check for thyroid antibodies in your blood. Your immune system makes antibodies to fight infections. If you have thyroid antibodies in your blood, you may have autoimmune thyroid disease. This can be a cause of an underactive thyroid. To read more about causes of the condition, see What is an underactive thyroid?
Your might also have blood tests to look for conditions that you can get alongside an underactive thyroid gland, such as raised cholesterol.
Seeing a specialist
Your doctor may refer you to a doctor who specialises in hormones (an endocrinologist) if you have any of the following: